The present invention relates to a new and improved construction of synchronization circuit for video clock oscillators.
In order to superimpose video images upon a screen it is necessary that the video signals, arriving from different video camera devices, be mutually synchronized. For this purpose all of the video cameras can be conjointly synchronized with the aid of the synchronization signals from one and the same synchronization clock source, which delivers a mixed pulse signal or a horizontal pulse signal in conjunction with a vertical pulse signal.
This simple method of synchronization of video images has however been found to be impractical, if there is not used a video camera which is not externally synchronized or if the synchronization problem resides in synchronizing video images corresponding to two or more different standards.